Mortgage Banking Activities, Assumptions and Sensitivity of Residential MSRs (Details) - Residential mortgage servicing rights [Member] $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2024 USD ($) $ / loan	Dec. 31, 2023 USD ($) $ / loan	Jun. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]
Mortgage servicing rights, carried at fair value	$ 6,544	$ 7,468	$ 7,061	$ 8,457	$ 8,251	$ 9,310
Expected weighted-average life (in years)	6 years 3 months 18 days	6 years 3 months 18 days
Key assumptions [Abstract]
Prepayment rate assumption	8.50%	8.90%
Impact on fair value from 10% adverse change	$ (196)	$ (224)
Impact on fair value from 25% adverse change	$ (472)	$ (538)
Discount rate assumption	9.60%	9.40%
Impact on fair value from 100 basis point increase	$ (259)	$ (294)
Impact on fair value from 200 basis point increase	$ (498)	$ (565)
Cost to service assumption ($ per loan) | $ / loan	104	105
Impact on fair value from 10% adverse change	$ (138)	$ (148)
Impact on fair value from 25% adverse change	$ (345)	$ (369)